This invention relates to horns for motor vehicles. Such horns conventionally include air horns, such as used on large trucks, which require a compressor and an air-operated horn. Other vehicles have electronically operated horns, which include a diaphragm that is subjected to an intermittent magnetic field to cause the diaphragm to vibrate producing a horn sound.
In most vehicles electrically operated horns fail from time to time and can be easily replaced when failure occurs. However, in vehicles used in certain environments, such as factories, warehouses, docks, mines, etc., safety regulations for operation may require frequent sounding of the vehicle horn. In such applications, the vehicle horn is subjected to more frequent use and failures occur more often than in vehicles used on the road. Further, a horn failure requires that the vehicle be taken out of operation for safety reasons.
It is an object of the present invention to provide a vehicles horn, wherein sound is generated electronically with components that have increased reliability.
In accordance with the present invention there is provided a horn for a motor vehicle having a read only memory with a memory space substantially filled with digital data representing a digitized horn sound. The memory is addressed by count signals from an N-bit counter which counts to its maximum count value in response to clock signals and thereafter repeats the count signals. The clock signals are provided by an oscillator. Data read from the memory in response to the count signals is provided to a digital-to-analog (D/A) converter which provides audio horn tone signals which are supplied to a speaker.
In one embodiment the memory may include first and second memory spaces, each substantially filled with data representing respective first and second horn sounds. At least one fixed address signal is selectable to select the desired horn sound.
In a preferred arrangement there is provided an amplifier for amplifying the audio signal.
According to the invention there is provided a method for providing a horn sound for a motor vehicle. Data representing a horn audio signal is recorded to substantially fill a contiguous addressable space of a digital memory. A continuous and repeating sequence of digital count signals are provided as address signals to the memory to continuously and repeatedly read out the data signals, which are converted to audio signals and broadcast by a speaker.
Preferably, a segment of the memory which includes all values of N address bits is substantially filled with the horn audio data.
For a better understanding of the present invention, together with other and further objects, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.